Rare Fossil Ammonite Kosmoceras obtusum Jurassic Lower Callovian Yorkshire UK COA

Description

Rare Kosmoceras obtusum Ammonite Fossil from South Newbald Quarry, Yorkshire

This listing presents a rare Kosmoceras obtusum ammonite fossil, discovered in the Lower Callovian Stage of the Middle Jurassic from South Newbald Quarry, Yorkshire, United Kingdom. Dating to approximately 166–163 million years ago, this specimen offers a genuine piece of British Jurassic history, showcasing the unique shell architecture and intricate ribbing typical of the species.

Each fossil we offer is 100% genuine and is supplied with a Certificate of Authenticity, guaranteeing both provenance and quality. The specimen shown in the photographs is the exact one you will receive, displayed with a 1 cm scale cube for accurate sizing reference.

Geological Context – Lower Callovian of the Jurassic

The Callovian Stage, part of the Middle Jurassic, was a period when much of northern Europe, including what is now Yorkshire, was covered by warm, shallow seas. These environments were ideal for marine life and created sedimentary deposits that are today some of the richest fossil-bearing strata in Britain.

South Newbald Quarry is a significant site for Callovian fossils, preserving a wide range of ammonites, bivalves, brachiopods, and marine reptiles. The presence of Kosmoceras obtusum in these deposits makes them invaluable to paleontologists, as ammonites are used as biostratigraphic markers to date and correlate Jurassic rock layers.

Scientific Classification

• Type: Ammonite Fossil
• Genus: Kosmoceras
• Species: obtusum
• Order: Ammonitida
• Superfamily: Stephanoceratoidea
• Family: Kosmoceratidae
• Age: Lower Callovian, Middle Jurassic (~166–163 million years ago)
• Locality: South Newbald Quarry, Yorkshire, United Kingdom

Morphological Features

This specimen of Kosmoceras obtusum displays the defining traits of the species, making it an excellent example for both collectors and scientific reference:

• Shell Form: A moderately involute shell with robust whorls.
• Ribbing: Coarse, well-defined ribs running across the flanks, typical of Kosmoceras ammonites.
• Tubercles: Nodular ornamentation along the ribs, enhancing both structural integrity and aesthetic appearance.
• Suture Pattern: Complex, frilled suture lines, characteristic of ammonites within the Stephanoceratoidea superfamily.

These features not only add to the visual appeal of the specimen but also provide insight into the evolutionary adaptations of Jurassic ammonites.

Paleoecological Insights

Ammonites such as Kosmoceras obtusum were nektonic predators, actively swimming in the shallow seas that covered Yorkshire during the Jurassic. They likely preyed on small crustaceans, mollusks, and other invertebrates, using their beak-like jaws and tentacles. In turn, ammonites were an important food source for larger predators, including ichthyosaurs and plesiosaurs.

The robust ribbing and tuberculation of Kosmoceras obtusum suggest adaptations that may have aided in buoyancy control and hydrodynamics, helping them thrive in dynamic marine ecosystems.

Collectability and Display Value

The combination of rarity, scientific significance, and striking preservation makes this Kosmoceras obtusum ammonite a highly desirable specimen. Its provenance from South Newbald Quarry in Yorkshire further enhances its value, as this locality is known for yielding exceptional Jurassic fossils.

This ammonite is ideal for fossil collectors, educational displays, or as a striking natural history piece. Its ribbed, tuberculate shell structure ensures it will stand out as a centerpiece in any collection.

Key Features

• Species: Kosmoceras obtusum
• Age: Lower Callovian, Middle Jurassic (~166–163 million years ago)
• Location: South Newbald Quarry, Yorkshire, UK
• Notable Traits: Coarse ribbing, tuberculate ornamentation, intricate suture lines
• Authenticity: Guaranteed genuine, with Certificate of Authenticity
• Exact Specimen: The item photographed is the exact fossil you will receive, measured with a 1 cm scale cube

This rare Kosmoceras obtusum ammonite fossil offers a tangible connection to Britain’s Jurassic seas and is an exceptional addition for both collectors and enthusiasts of natural history.